This invention relates to a variable velocity air curtain for a refrigeration display case.
Supermarkets and retailers of other perishable goods use refrigerator display cases to both refrigerate and display such goods. Generally, these display cases are simple and unsophisticated refrigeration units that comprise a case and an open viewing area that permits consumers to reach into the refrigerated section of the case to retrieve the perishable item. A curtain of air is typically blown across the viewing area from the top of the case down to a warm air return at the bottom of the case. The air travels to an air inlet of the return that feeds the air back to a fan that draws the air not only into the inlet but across an evaporator coil that cools the air. The fan is fixed in speed, blowing a constant amount of air across the viewing area. This air curtain serves to create a wall of air that prevents warm air from outside of the case from entering the interior of the case.
Given the open nature of the display case, environmental conditions may affect the interior temperature of the refrigeration unit. Specifically, if the temperature of a location, such as a store, is high, the interior of the display case may also warm. Moreover, frequent intrusion into the display cases"" interior by consumers reaching for and removing product may also affect the temperature within the interior. Current systems have few effective mechanisms for addressing changing exterior and interior environmental conditions about the refrigeration display case.
A need therefore exists for a display case that may account for these environmental conditions and cool the interior of the display case in a cost effective manner.
The invention comprises a refrigeration display case that employs an environmental sensor and a control unit that controls the fans to alter the rate of air flow across the viewing area of the display case. The refrigeration system comprises a display case, an evaporator coil, fans, a viewing area set across the display case, at least one sensor for obtaining environmental data, and a control unit. The control unit controls the speed of the fans based on the sensed environmental data.
By controlling the speed of the fans, the control unit alters the rate of air moved across the viewing area, providing more or less cold air depending on the sensed environmental conditions. The control unit may adjust the rate of air by altering the speed of the fan, altering the Hertz rating of the fan, or altering the angle of the fan blades of the fan.
Additionally, the control unit may control more than one fan separately. This allows the control unit to alter the rate of air moved by each of the fans together or differently. The control unit may receive environmental data from a wide variety of sensors. One sensor may provide data on air pressure. Another sensor may provide data concerning ambient humidity. Moreover, the environmental sensor may also sense temperature. The environment may be sensed both inside of the display case and outside of the display case. This data is communicated to the control unit which makes a determination as to the correct amount of air required for the specific environmental conditions.
In this way, the refrigeration system offers an inexpensive and efficient mechanism for accommodating the changing environmental conditions in a supermarket or other retail establishment. The refrigeration system has the opportunity to obtain a wide variety of environmental data and make intelligent decisions to control temperature within the display case. This system may be employed practically because it may incorporate existing sensors and computer controls.